This invention relates to a torque transfer gear assembly for supply of drive power to either 2 or 4 wheels of a vehicle and more particularly to a gear transfer unit having an input shaft and two output shafts with different angular output orientations to permit optimization of orientation of the unit and at the same time facilitating ready aligned connection to the front and rear drive shafts of the vehicle.
Torque transfer mechanisms for supply of drive power to four wheels of a vehicle are usually connected to the vehicle transmission which in turn is connected to be driven by the vehicle engine. The torque transfer unit is thus an extension of the engine and transmission drive train and its location, usually under the driver's compartment, is limited in range by the important considerations of effectiveness and efficiency of operation of the power supply train and need for accommadation to the presence of other adjacent automotive components such as exhaust system components. When the engine is located over the front wheels of the vehicle, as is generally the case, the engine and its connected transmission and torque transfer units are angled downwardly in alignment with the rear drive shaft leading to the rear wheel differential. Customarily the front and rear output shafts of the transfer unit such as a conventional five gear transfer unit, however, are parallel with the input shaft, and the front wheel output shaft is therefore usually not oriented optimally for ready connection with the front wheel drive shaft. In other words, the transfer unit in connection with the engine and transmission can be aligned in straight line relation with the rear wheel shaft, but this does not place the front output shaft of the transfer unit in proper orientation for straight line connection with the front drive shaft to the front differential. This inability to establish straight alignment with the front drive shaft can be compensated for to a degree by special joints and, in some cases to a degree by compound double angular joints, but such joints are usually less than desirable because of their complexity in mechanics and dynamics of operation, need for care and costliness.